Mr Johnson was a top donor to Mr Trump during the presidential campaign, and was named in November as finance chair of his inaugural committee.

A long-time Republican donor, Mr Johnson helped raise money for George W Bush, John McCain and Mitt Romney when they were the party's nominees. He served as finance chairman for Jeb Bush earlier in the 2016 campaign.

Matthew Barzun was the previous US ambassador to the UK. He was appointed in 2013 by Barack Obama and stepped down in January this year, before Mr Trump's inauguration.

Woody Johnson (L) with Rudy Giuliani, the former New York mayor and his wife Judith Nathan GiulianiCredit:
Connor/Variety/REX/Shutterstock

Mr Johnson's residence in London will be Winfield House, a mansion in Regent's Park that boasts 12 acres of grounds - second only to Buckingham Palace in terms of largest private gardens in the capital.